1. Field of the Invention
The present invention generally relates to the electronics industry and, more specifically, the cleaning of masks used to form patterns on a substrate.
2. Discussion of the Related Art
Currently, the cleaning of the masks used in the electronics industry is performed in an aqueous medium by means of solutions generally containing sulfates. This processing is performed outside of the semiconductor manufacturing installations and exhibits several disadvantages.
A first disadvantage is the routing of the masks to be cleaned to another installation, generally that of the mask manufacturer. Indeed, the controlled atmosphere of the “clean room” should be respected as much as possible and any entrance-exit of material poses a problem.
Another disadvantage is the use of solutions based on sulfates for the cleaning. Indeed, gas residues (H2SO4) remain present at the return of the mask in the clean room. The presence of ammonia (NH3) in the clean room (compound widely used in semiconductor manufacturing) then favors the subsequent growth of ammonium sulfate salts (NH4)2SO4 at the mask surface. This pollution adds to that coming from the other gases present in the installation.
Further, all the processings aiming at decreasing the deposition of salts on masks (for example, the maintaining of a controlled air flow during the exposure to light) only space apart the cleanings and impose constraints in the clean room, which increases the general manufacturing costs of electronic circuits.